Gene characterized for membrane desaturase that produces ( E )-11 isomers of mono- and diunsaturated fatty acids

Abstract

Moth species have evolved integral membrane desaturases that exhibit a wide diversity in substrate specificity, as well as in regiospecificity and stereospecificity of the unsaturated products. We report here the cloning and expression of a single desaturase from the sex pheromone gland of the light brown apple moth, Epiphyas postvittana, that makes E11 isomers of monounsaturated (E11-16 and E11-14) fatty acids and a diunsaturated (E9,E11-14) fatty acid. In the pheromone gland, the monoene precursor is made available by ␤ oxidation of E11-16 acid with a subsequent twocarbon loss to E9-14 acid. A functional assay using a baculovirus expression system required addition of myristic acid and E9-14 acid precursors to demonstrate the unusual regiospecificity and stereospecificity of this desaturase. The amino acid sequence of this desaturase has Ϸ61% identity to that of Z11-desaturases from two other insect species, and only Ϸ48% identity to the metabolic Z9-desaturases in those species. A pheromone-gland Z9-desaturase gene also was found with the light brown apple moth that differed in its deduced amino acid sequence (66% identity) with the metabolic Z9-desaturase from fat body in this species.

A multifunctional desaturase involved in the biosynthesis of the processionary moth sex pheromone

“…Several ⌬ 9 desaturases have been cloned from moth pheromone glands and functionally expressed in yeast (6,8,10,18,24). However, none of the multiple clones from T. pityocampa pheromone glands analyzed corresponded to a ⌬ 9 desaturase.…”

“…The desaturases expressed in female sex-pheromone glands of different moth species have evolved to play a key role in the biosynthesis of sex pheromones, exhibiting an amazing diversity of substrate and regio-and stereospecifities. Unlike the metabolic ⌬ 9 acyl-CoA desaturases, pheromone gland desaturases catalyze the formation of uncommon unsaturated fatty acyl-CoA esters with variable chain lengths, different locations of unsaturations, and either the ordinary Z or the unusual E double bond geometry (3)(4)(5)(6)(7)(8)(9)(10).…”

Evolution of multicomponent pheromone signals in small ermine moths involves a single fatty-acyl reductase gene

“…To assess the reliability of tissue distribution patterns and phylogenetic studies in predicting the functionality of pheromone biosynthetic lepidopteran FARs, Yev-FARI or Yev-FARIII were included as controls. Yeast cells were incubated for 24 h in the presence of galactose and equal concentrations of individually supplied FAME precursors (17,33) before extraction with n-hexane and GC-MS analyses. Yeast cells supplemented with fatty-acyl moieties and expressing Yev-pgFAR did catalyze the formation of primary fatty alcohols, whereas yeast cells transformed with the pYES2.1 expression vector alone did not convert any acyl substrate (Fig.…”

Biotechnological potential of insect fatty acid-modifying enzymes

“…In addition to the ability to introduce Z-double bonds, moth mFADs can catalyze the introduction of rather uncommon E-double bond in nature [64][65][66][67][68] or produce a mixture of E-and Z-unsaturated FAs [69,70]. The preferred fatty acyl chain length may be C14 [27,[66][67][68][70][71][72][73], C16 [74], or C18 [63,75,76], but some mFADs can desaturate a broad range of fatty acyl chain lengths, such as C14-C20 [67,77]. The positions of the introduced double bond include ∆9, ∆4 [33], ∆5 [72], ∆6 [64,78], ∆8 [65], ∆10 [69,78], ∆11 [10, 63, 65-67, 74-76, 79, 80], ∆13 [81], and ∆14 [70,82].…”

“…Δ12 mFADs have also been identified, but they are involved in primary metabolism during the production of methylene-interrupted PUFAs [31] rather than pheromone biosynthesis. The moth mFADs can also introduce a double bond at the terminal position between the penultimate and ultimate carbon atoms [78,83] and can produce FAs with a system of isolated double bonds [64] or a system of conjugated double bonds [10,65,66,76,79,80,82]. Among the more bizarre desaturation reactions, an mFAD identified in the processionary moth, Thaumetopoea pityocampa, can introduce triple bonds into the FA chains [81], resembling in activity an mFAD described in the plant of Crepis genus [84].…”